1. Field of the Invention
The present invention relates to an improvement in the distillation structures used in the process of catalytic distillation. More particularly the invention relates to the distillation structures using catalyst particles which change shape and/or size.
2. Related Art
A new method of carrying out catalytic reactions has been developed, wherein the components of the reaction system are concurrently separable by distillation, using the catalyst structures as the distillation structures, the method being commonly referred to as Catalytic Distillation. Such systems are described variously in U.S. Pat. Nos. 4,215,011; 4,232,177; 4,242,530; 4,302,356; 4,307,254; 4,336,407; 4,439,350; 4,443,559; and 4,482,775.
Briefly, a preferred and commercial catalyst structure described in the above patents comprises a cloth belt with a plurality of pockets spaced along the belt and containing particulate catalyst material, said cloth belt being wound in a helix about a spacing material such as stainless steel knitted mesh. These units are then disposed in the distillation column reactor. In addition, U.S. Pat. Nos. 4,443,559 and 4,250,052 disclose a variety of catalyst structures for this use and are incorporated herein.
Some particulate catalyst materials tend to swell and contract under various conditions. For example, cation exchange resins swell in contact with hydrocarbons. The arrangement of the catalyst particles in cloth pockets as described in the above cited patents, does allow for some expansion within the pockets, however, the catalysts particles at the bottom of vertically positioned catalyst units is constricted by the catalyst above them in the pocket